The present invention relates to a method of thermoluminescent dosimetry and more particularly to such method in which reading of thermoluminescent dosimeter is preformed by infrared beam heating.
In thermoluminescent dosimetry, heating of the dosimeter element is one of the important techniques. The heating must meet the following two requirements.
(1) To rapidly reach the required temperature (generally 250.degree. C. to 300.degree. C.). PA0 (2) Not to exceed 400.degree. C. (because the noise signal of thermal radiation becomes remarkably large at temperatures above 400.degree. C.).
The temperature of requirement (1) is the emission completing temperature which is defined as follows:
It is known the thermoluminescence is completely emitted when a dosimeter is heated to the specified temperature which value is dependent upon the phosphor material. It is also known that if the heating of the dosimeter is kept at a temperature below this specified temperature, it takes an extreamly long time to complete the emission of thermoluminescence. This specified temperature is referred to hereinafter as the emission completing temperature.
Hitherto developed techniques are contact heating, heating by hot air jet, heating by infrared beam and heating by high frequency induction. Heating by hot air jet can easily meet the requirement because it assumes a temperature-controlled system. This technique, however, has a difficulty in that it requires a large-scale heat-exchanger for obtaining the hot air jet.
On the other hand, heating by infrared beam enables non-contact heating by a simple construction and enables exclusive heating of small area. However since this technique must essentially be a heating-power controlled type, above-mentioned requirements cannot be easily met thereby.